Embodiments of the invention relate to a magnetically geared machine, such as motors and generators, and more particularly, to a magnetically geared machine having a cooling concept integrated therein.
Electrical machines (e.g., motors, generators) typically deliver more power at high speeds than at low speeds. In order to adapt a high-speed, rotating electrical machine to a high-torque, lower speed mechanical component (e.g., a prime mover in the case of a generator and a load in the case of a motor), mechanical gear boxes are extensively used, as the cost of having a high-speed electrical machine coupled with corresponding mechanical gearing for speed/torque conversion is lower than that for a low-speed electrical machine. Certain disadvantages are inherent with mechanical gearing such as, for example, acoustic noise, vibration, reliability and the need for lubrication and maintenance, to name a few.
In conventional electromagnetic machines having mechanical gearing, the cooling is an essential aspect for the functionality of the machine. However, due to the limitations in the design of conventional electromagnetic machines, it is only possible to use the mechanical gap between moving part and stationary part of the machine. In some electromagnetic machines air or other cooling medium is distributed through the gap to carry away the undesired heat from the magnetic active parts. Although it is desirable to have a large or broad air gap for cooling purposes, for proper functioning of the machine, it is desirable to have a small mechanical gap. Also, typically only air is used as cooling medium in such systems. Air has a relatively low heat carrying capacity compared to other fluids.
Accordingly, it is desirable to have an electrical machine that has provision for cooling purposes.